This invention relates to an apparatus for judging the surface condition of a metal such as an aluminum film deposited on a semiconductor wafer.
To form an aluminum deposition film on a semiconductor wafer is an indispensable step in the manufacture of a semiconductor product. Between the surface of a pad made of such aluminum deposition film formed on a discrete semiconductor device or chip and an external terminal provided on a lead frame, thin aluminum or gold leads are bonded. The aluminum deposition film thus is required to always have a satisfactory bonding property with respect to aluminum or gold thin leads. The judgement of the bonding property usually has been made by visually inspecting the surface of the aluminum deposition film that is formed on a semiconductor wafer. The aluminum deposition film generally has a mirror like smooth surface, that is, its bonding property generally is satisfactory. If gas such as CO.sub.2 remains in a deposition apparatus in the depositing step, the film deposited on the wafer has a rough surface, that is, its bonding property is deteriorated. This rough surface looks whitish and thus permits distinguishment of the unsatisfactory bonding property. However, a deposition film which has a satisfactory bonding property although its surface is whitish may be formed depending upon conditions at the time of the deposition. For example, when aluminum is deposited while maintaining a comparatively high wafer temperature or when it is deposited to a thickness in excess of 2 .mu.m its crystal growth occurs on the wafer. The deposition film in this case has a whitish surface, but its bonding property is satisfactory. When the bonding property is judged by visual inspection, a surface of crystal growth is often rejected in spite of its satisfactory bonding property because its surface looks whitish.